Field of the Invention
This application is directed to systems and methods for treating occlusions, including crossing narrow passages of lumen segments or total occlusions.
Description of the Related Art
A variety of techniques exist to de-bulk occluded vessel segments. While these techniques have met varying degrees of success, not all patients are successfully treated in this manner. Some patients with peripheral occlusions are left with few options other than amputation of the limb fed by the occluded artery. Such drastic techniques are obviously not available to patients with extensive occlusion of coronary and other critical arteries.
There are a number of products on the market that are designed specifically for crossing CTOs and these can be categorized as either intraluminal, subintimal or re-entry devices. Intraluminal crossing in theory may reduce the dissection plane of a long occlusive lesion, protect collaterals and keep treatment options open. Subintimal crossing may extend “re-entry” beyond the occluded segment, putting collaterals at risk and limiting treatment options. It may also increase the rates of complications such as perforation and dissection and extend procedure time with resultant increased radiation and contrast exposure. Also below the knee, once a wire has crossed into the adventitia it can be extremely difficult to re-enter the true lumen.
Certain catheter systems have been developed to cross occlusions in an intraluminal manner. However, these catheter systems have problems. For instance three or more coaxially placed catheter bodies can work in a system to cross a lesion. An inner solid guidewire member can be provided within an outer sheath. An intervening rotatable layer can be advanced over the guidewire from within the outer sheath to gouge or chisel the occlusion mass slowly away. One problem with this structure is that with three or more components, two operators may be needed to handle components of the device.
Also, with more calcified lesions typical catheter bodies are not well suited to provide access. Generally, catheter bodies are of reduced stiffness toward the distal end thereof to minimize potential for trauma to healthy vascular tissues. However, in order operate on highly calcified lesions, the tip of the device should have greater stiffness.
Another problem with conventional techniques is (i.e., atherectomy-devices) is that debris of atheroma may embolize and may lead to distal embolization including no-reflow phenomenon. In addition, for these devices greater arterial access sheaths are mandatory, which lead to more vascular complications in this normally very ill patients.